Industrial dryers used in hotels and the like sometimes employ dryer blocks that are mounted inside the dryer to condition fabrics and the like being dried. The dryer blocks condition the fabrics and the like for such reasons as to prevent static, to provided a fabric softener sanitizer, to provide a water repellant, to provide a deodorizer, to provide a bleach, to provide a soil repellant, to provide due-transfer inhibitors, to provide fiber protecting polymers, to provide fiber smoothers, to provide UV light absorbers, to provide anti-wrinkle agents, etc. The dryer blocks include a solid product of select substances that rubs off on the materials as the materials engage the solid product in a rotating drum of the dryer. After a period of time a substantial portion of the solid product is rubbed off and should be replaced.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a method of indicating to the operator that it is time to replace the solid product.